Select Committee on Science and Technology Written Evidence


Memorandum by the Institute of Food Research

  The Institute of Food Research (IFR) welcomes the Government's recent infectious disease strategy, Getting Ahead of the Curve. IFR is a BBSRC-sponsored Institute with a major research portfolio in Food Safety Science. The following comments are made from the perspective of microbiological food safety and exclude consideration of non-food-borne disease. The questions are those listed in the Call for Evidence.

1.   What are the main problems facing the surveillance, treatment and prevention of human infectious disease in the United Kingdom?

  The prevention of food-borne disease is not a static problem, on account of factors such as pathogen evolution, changes in agricultural production methods, food processing regimes, demographic factors and consumer habits. A range of initiatives—long-term, short-term and contingency—are necessary, some of which will interface directly with industry and with consumers, whilst others will be directed towards the fundamental biology of food-borne pathogens and host responses. Maintaining a perspective on the whole production and consumption chain ("from fork to farm"), rather than dealing with individual steps or processes in isolation, is essential. An effective and co-ordinated national skill base in surveillance, epidemiology and diagnostic microbiology remains vital.

  The following are in general medium- and longer-term issues that in our view must be addressed to provide the underpinning knowledge essential to effective prevention and control of food-borne disease.

  (i)   Recognising the organisms that are the causes of food-borne disease. In a substantial proportion of food-poisoning outbreaks, the organisms responsible are not unequivocally identified; therefore the source of the outbreak and the mode of transmission remain uncertain. Our understanding of the contribution made to outbreaks by less well-publicised pathogens (eg Clostridium perfringens; foodborne viral agents) remains incomplete whilst in other organisms, for example Campylobacter spp, the characteristics that distinguish virulent and non-virulent strains still remain poorly defined. More importantly, the emergence of new pathogens may not be immediately recognised. More resources devoted to surveillance and microbiological identification will help to address these issues.

  (ii)   Understanding the factors that cause, or prevent, the proliferation of food-borne pathogens. Substantial progress has been made in the development and application of mathematical modelling techniques to predict microbial growth in a range of food environments. Our own work at IFR has been at the forefront of these developments. This work and its industrial application are particularly important in the light of increasing sales and consumption of minimally processed, chilled foods, prepared without the use of traditional processing methods such as canning or freezing.

  Predictive microbiology must continue to be underpinned by studies of fundamental physiology—both at the level of the single organism (eg to understand the control of spore germination) and also at the population level (eg to understand the basis of the quorum-sensing mechanisms that determine responses to population density). The transmission of food-borne pathogens depends critically upon their survival in the face of environmental stresses (eg desiccation; heat/cold shock) and stresses within the host (eg stomach acid). Such responses are still very imperfectly understood, particularly in relatively poorly characterised organisms such as Campylobacter spp. Finally, it is important to understand the processes that drive the selection and emergence of variant individuals in response to environmental factors—variants that may, for example, be unusually resistant to normal food preparation or preservation regimes or that may display altered virulence characteristics.

  (iii)   Understanding host-pathogen interactions. There has been enormous progress in understanding the molecular mechanisms by which (some) bacterial pathogens can survive and proliferate in an animal or human host and cause disease. This has been facilitated by the development of techniques to study gene function at the level of the single bacterial cell, leading (in particular) to the identification of genes (eg in Salmonella spp) that are critical to the successful invasion of host cells. In addition, it is particularly important to understand gastrointestinal and immunological factors that determine whether or not disease will develop, and the variation of these factors between individuals and between population groups. Maintenance and/or manipulation of the native flora of the gastrointestinal tract may provide an effective means to exclude colonisation by pathogens and may assist in the prevention of other diseases, such as colon cancer. Analogously, in pigs and poultry, colonisation of the gastrointestinal tract by food pathogenic bacteria may be prevented by "competitive exclusion" with non-harmful organisms. This can provide a non-antibiotic-based strategy to reduce the burden of food-borne pathogens at slaughter.

  (iv)   Information provision and education. Good practices depend upon awareness and training provided or promoted by the education sector, industry, and learned societies and professional bodies. Balanced and accessible information provision to consumers is vital, both to promote safe practices in food preparation and consumption and to ensure that consumers gain an authoritative, objective assessment of food-associated risks, including in those cases (notably the BSE episode) where scientific evidence may at the time be insufficient to provide an accurate and informed estimate of risk. The agri-food industry is critically dependent upon consumer confidence and upon national and international reputation and this requires the establishment of a climate of trust.

  There are important issues to be considered in ensuring that information that is received and understood by its target audience is actually effective in modifying behaviour. The notified incidence of food poisoning has increased significantly in recent years. Although consumer concern about microbiological food hazards is relatively high, protective behaviour is low, since in general people believe that they as individuals are at low risk from food poisoning (particularly from food prepared in the home). Work at IFR and elsewhere has shown that public perception of food poisoning is prone to optimistic bias, in which people believe that they are less at risk from a hazard than comparable other people. Optimistic bias may adversely affect risk communication and may impact on the success of public health campaigns aimed at increasing self-protective behaviour. It has been argued that such campaigns are unsuccessful because they fail to change the perception of personal invulnerability. Thus, whilst people may rate a hazard as more risky generally following such a campaign, they may not change their rating of personal susceptibility. It has been shown that there is a disparity between food safety knowledge and self-reported practices, in that people are aware of self-protective behaviours, but nevertheless do not use safe food handling practices.

2.   Will these problems be adequately addressed by the Government's recent infectious disease strategy, Getting Ahead of the Curve?

  "Getting Ahead of the Curve" sets out important new recommendations to identify and deal with the threats posed by infectious disease, including recommendations on education and information provision, and proposes a rationalised management structure for microbiology laboratories undertaking diagnosis, profiling and surveillance work. The document does not, however, present a review of current staffing and other resources, and whether these will in future be adequate. The relationships between the proposed National Infection Control and Health Protection Agency and the Food Standards Agency (which will retain responsibility for food safety) are not defined in the document, but we assume that suitable arrangements for joint working will be put in place. We presume that there will be mechanisms to ensure a concerted approach to research on infectious diseases that will not only involve the new Agency and MRC but also FSA, BBSRC and other relevant bodies.

3.   Is the United Kingdom benefiting from advances in surveillance and diagnostic technologies: if not, what are the obstacles to its doing so?

  As pointed out in "Getting Ahead of the Curve", the UK has a strong competence in surveillance and in the application of new technologies in this area. Both traditional microbiological skills and new genomic and "phenomic" profiling techniques are necessary; reliance on too narrow a skill base (even if modern) is potentially dangerous.

4.   Should the United Kingdom make greater use of vaccines to combat infection and what problems exist for developing new, more effective or safer vaccines?

  Most food-borne diseases in the UK are not a priority for the development of vaccines for humans. On the other hand, organisms used as food (food plants and lactic acid bacteria) can provide in principle promising vehicles for the delivery of oral vaccines against other infectious diseases.

  It may be economic to develop and employ vaccines against common food-borne pathogens, such as Campylobacter, in food-animal hosts (cf. also comment on "competitive exclusion" of food-borne pathogens in 1. iii above).

5.   Which infectious diseases pose the biggest threats in the foreseeable future?

  Food-borne diseases impose a major health and economic burden on the UK, though for many of those affected the consequences are short-lived. The emergence of new food-borne pathogens is an ever-present threat and there is also the possibility of the emergence of new and more virulent strains of already-known food-borne pathogens; since several new or more virulent pathogens have emerged in the last few decades, it is not unlikely that more may arise in the future. We would emphasise particularly the importance of minimising the use of antibiotics in food production in preventing the emergence of antibiotic-resistant strains.

  Food-borne pathogens are potentially agents for use by bioterrorists.

6.   What policy interventions would have the greatest impact on preventing outbreaks of and damage caused by infectious disease in the United Kingdom?

  This is difficult to judge, since as indicated above, an effective prevention policy requires the orchestration of a variety of complementary functions and initiatives—surveillance, diagnosis, research, education and training, and information provision.

  Import controls and immigration procedures have an obvious and vital role to play in controlling the import of potentially infective materials, such as meat and meat products that may harbour new pathogen strains (including antibiotic-resistant strains). This may become an even more important issue with the enlargement of the European Union.

  We hope that these comments will be useful to the Sub-Committee in considering the Government's Report and the future strategies for the surveillance and prevention of infectious disease. Please do not hesitate to get in touch if we can be of further assistance.

Dr Nick Walton

(Senior Scientist—Communications)

October 2002


 
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